From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E328C3DA7A for ; Thu, 5 Jan 2023 03:49:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231248AbjAEDtM (ORCPT ); Wed, 4 Jan 2023 22:49:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231667AbjAEDs4 (ORCPT ); Wed, 4 Jan 2023 22:48:56 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 699AA574D2; Wed, 4 Jan 2023 19:46:28 -0800 (PST) Received: from lhrpeml500004.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4NnXQL4Rf0z6J6cN; Thu, 5 Jan 2023 11:44:10 +0800 (CST) Received: from [10.123.123.126] (10.123.123.126) by lhrpeml500004.china.huawei.com (7.191.163.9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Thu, 5 Jan 2023 03:46:25 +0000 Message-ID: <94a8ef89-b59e-d218-77a1-bf2f9d4096c7@huawei.com> Date: Thu, 5 Jan 2023 06:46:24 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.1 Subject: Re: [PATCH v8 11/12] samples/landlock: Add network demo Content-Language: ru To: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= CC: , , , , , References: <20221021152644.155136-1-konstantin.meskhidze@huawei.com> <20221021152644.155136-12-konstantin.meskhidze@huawei.com> <2ff97355-18ef-e539-b4c1-720cd83daf1d@digikod.net> From: "Konstantin Meskhidze (A)" In-Reply-To: <2ff97355-18ef-e539-b4c1-720cd83daf1d@digikod.net> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.123.123.126] X-ClientProxiedBy: lhrpeml500001.china.huawei.com (7.191.163.213) To lhrpeml500004.china.huawei.com (7.191.163.9) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 11/16/2022 5:25 PM, Mickaël Salaün пишет: > > On 21/10/2022 17:26, Konstantin Meskhidze wrote: >> This commit adds network demo. It's possible to allow a sandboxer to >> bind/connect to a list of particular ports restricting network >> actions to the rest of ports. >> >> Signed-off-by: Konstantin Meskhidze >> --- >> >> Changes since v7: >> * Removes network support if ABI < 4. >> * Removes network support if not set by a user. >> >> Changes since v6: >> * Removes network support if ABI < 3. >> >> Changes since v5: >> * Makes network ports sandboxing optional. >> * Fixes some logic errors. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and >> ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables >> to insert TCP ports. >> * Renames populate_ruleset() to populate_ruleset_fs(). >> * Adds populate_ruleset_net() and parse_port_num() helpers. >> * Refactors main() to support network sandboxing. >> >> --- >> samples/landlock/sandboxer.c | 129 +++++++++++++++++++++++++++++++---- >> 1 file changed, 116 insertions(+), 13 deletions(-) >> >> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c >> index fd4237c64fb2..68582b0d7c85 100644 >> --- a/samples/landlock/sandboxer.c >> +++ b/samples/landlock/sandboxer.c >> @@ -51,6 +51,8 @@ static inline int landlock_restrict_self(const int ruleset_fd, >> >> #define ENV_FS_RO_NAME "LL_FS_RO" >> #define ENV_FS_RW_NAME "LL_FS_RW" >> +#define ENV_TCP_BIND_NAME "LL_TCP_BIND" >> +#define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" >> #define ENV_PATH_TOKEN ":" >> >> static int parse_path(char *env_path, const char ***const path_list) >> @@ -71,6 +73,20 @@ static int parse_path(char *env_path, const char ***const path_list) >> return num_paths; >> } >> >> +static int parse_port_num(char *env_port) >> +{ >> + int i, num_ports = 0; >> + >> + if (env_port) { >> + num_ports++; >> + for (i = 0; env_port[i]; i++) { >> + if (env_port[i] == ENV_PATH_TOKEN[0]) >> + num_ports++; >> + } >> + } >> + return num_ports; >> +} >> + >> /* clang-format off */ >> >> #define ACCESS_FILE ( \ >> @@ -81,8 +97,8 @@ static int parse_path(char *env_path, const char ***const path_list) >> >> /* clang-format on */ >> >> -static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> - const __u64 allowed_access) >> +static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd, >> + const __u64 allowed_access) >> { >> int num_paths, i, ret = 1; >> char *env_path_name; >> @@ -143,6 +159,48 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> return ret; >> } >> >> +static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, >> + const __u64 allowed_access) >> +{ >> + int num_ports, i, ret = 1; >> + char *env_port_name; >> + struct landlock_net_service_attr net_service = { >> + .allowed_access = 0, >> + .port = 0, >> + }; >> + >> + env_port_name = getenv(env_var); >> + if (!env_port_name) { >> + ret = 0; >> + goto out_free_name; > > This is a bug because env_port_name is not allocated. This should simply > return 0. > > >> + } >> + env_port_name = strdup(env_port_name); >> + unsetenv(env_var); >> + num_ports = parse_port_num(env_port_name); >> + >> + if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) { >> + ret = 0; >> + goto out_free_name; >> + } >> + >> + for (i = 0; i < num_ports; i++) { >> + net_service.allowed_access = allowed_access; >> + net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN)); >> + if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE, >> + &net_service, 0)) { >> + fprintf(stderr, >> + "Failed to update the ruleset with port \"%d\": %s\n", >> + net_service.port, strerror(errno)); >> + goto out_free_name; >> + } >> + } >> + ret = 0; >> + >> +out_free_name: >> + free(env_port_name); >> + return ret; >> +} >> + >> /* clang-format off */ >> >> #define ACCESS_FS_ROUGHLY_READ ( \ >> @@ -164,41 +222,63 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd, >> LANDLOCK_ACCESS_FS_REFER | \ >> LANDLOCK_ACCESS_FS_TRUNCATE) >> >> +#define ACCESS_NET_BIND_CONNECT ( \ >> + LANDLOCK_ACCESS_NET_BIND_TCP | \ >> + LANDLOCK_ACCESS_NET_CONNECT_TCP) > > You can remove ACCESS_NET_BIND_CONNECT and make the underlying access > rights explicit. > > >> + >> /* clang-format on */ >> >> -#define LANDLOCK_ABI_LAST 3 >> +#define LANDLOCK_ABI_LAST 4 >> >> int main(const int argc, char *const argv[], char *const *const envp) >> { >> const char *cmd_path; >> char *const *cmd_argv; >> int ruleset_fd, abi; >> + char *env_port_name; >> __u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ, >> - access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE; >> + access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE, >> + access_net_tcp = ACCESS_NET_BIND_CONNECT; >> struct landlock_ruleset_attr ruleset_attr = { >> .handled_access_fs = access_fs_rw, >> + .handled_access_net = access_net_tcp, >> }; >> >> if (argc < 2) { >> fprintf(stderr, >> - "usage: %s=\"...\" %s=\"...\" %s [args]...\n\n", >> - ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]); >> + "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " >> + " [args]...\n\n", >> + ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, >> + ENV_TCP_CONNECT_NAME, argv[0]); >> fprintf(stderr, >> "Launch a command in a restricted environment.\n\n"); >> - fprintf(stderr, "Environment variables containing paths, " >> - "each separated by a colon:\n"); >> + fprintf(stderr, >> + "Environment variables containing paths and ports " >> + "each separated by a colon:\n"); >> fprintf(stderr, >> "* %s: list of paths allowed to be used in a read-only way.\n", >> ENV_FS_RO_NAME); >> fprintf(stderr, >> - "* %s: list of paths allowed to be used in a read-write way.\n", >> + "* %s: list of paths allowed to be used in a read-write way.\n\n", >> ENV_FS_RW_NAME); >> + fprintf(stderr, >> + "Environment variables containing ports are optional " >> + "and could be skipped.\n"); >> + fprintf(stderr, >> + "* %s: list of ports allowed to bind (server).\n", >> + ENV_TCP_BIND_NAME); >> + fprintf(stderr, >> + "* %s: list of ports allowed to connect (client).\n", >> + ENV_TCP_CONNECT_NAME); >> fprintf(stderr, >> "\nexample:\n" >> "%s=\"/bin:/lib:/usr:/proc:/etc:/dev/urandom\" " >> "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" " >> + "%s=\"9418\" " >> + "%s=\"80:443\" " >> "%s bash -i\n\n", >> - ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]); >> + ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, >> + ENV_TCP_CONNECT_NAME, argv[0]); >> fprintf(stderr, >> "This sandboxer can use Landlock features " >> "up to ABI version %d.\n", >> @@ -240,7 +320,10 @@ int main(const int argc, char *const argv[], char *const *const envp) >> case 2: >> /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */ >> ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE; >> - >> + __attribute__((fallthrough)); >> + case 3: >> + /* Removes network support for ABI < 4 */ >> + ruleset_attr.handled_access_net &= ~ACCESS_NET_BIND_CONNECT; > > You can check the TCP environment variables here and error out if one is > set. > > Please keep the newline here. > > >> fprintf(stderr, >> "Hint: You should update the running kernel " >> "to leverage Landlock features " >> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp) >> access_fs_ro &= ruleset_attr.handled_access_fs; >> access_fs_rw &= ruleset_attr.handled_access_fs; >> >> + /* Removes bind access attribute if not supported by a user. */ >> + env_port_name = getenv(ENV_TCP_BIND_NAME); >> + if (!env_port_name) { > > You can move this logic at the populate_ruleset_net() call site and > update this helper to not call getenv() twice for the same variable. But here I exclude ruleset attributes, not rule itself. It will break the logic: creating a ruleset then applying rules. I suggest to leave here as its. > > >> + access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP; >> + } >> + /* Removes connect access attribute if not supported by a user. */ >> + env_port_name = getenv(ENV_TCP_CONNECT_NAME); >> + if (!env_port_name) { >> + access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP; >> + } >> + ruleset_attr.handled_access_net &= access_net_tcp; > > There is no need for access_net_tcp. > >> + >> ruleset_fd = >> landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); >> if (ruleset_fd < 0) { >> perror("Failed to create a ruleset"); >> return 1; >> } > > newline > >> - if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) { >> + if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) { >> + goto err_close_ruleset; >> + } >> + if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { >> + goto err_close_ruleset; >> + } > > newline > >> + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, >> + LANDLOCK_ACCESS_NET_BIND_TCP)) { >> goto err_close_ruleset; >> } >> - if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) { >> + if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd, >> + LANDLOCK_ACCESS_NET_CONNECT_TCP)) { >> goto err_close_ruleset; >> } > > newline > >> if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) { >> -- >> 2.25.1 >> > .